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The Human

2 of 3 chapter 1

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the human

• Lecture 2 Information i/o … • visual, auditory, haptic, movement

• Lecture 3 (today)– Information stored in memory

• sensory, short-term, long-term

• Lecture 4– Information processed and applied

• reasoning, problem solving, skill, error

– Emotion influences human capabilities– Each person is different

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Memory

There are three types of memory function:

Sensory memories

Short-term memory or working memory

Long-term memory

Selection of stimuli governed by level of arousal.

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Sensory memory

• Buffers for stimuli received through senses– iconic memory: visual stimuli– echoic memory: aural stimuli– haptic memory: tactile stimuli

• Examples– “sparkler” trail– stereo sound

• Continuously overwritten

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Short-term memory (STM)

• Scratch-pad for temporary recall– rapid access ~ 70ms– rapid decay ~ 200ms– limited capacity - 7± 2 chunks

• Some research suggests that programmers have better short-term memory than ‘average’ people– This means you will have better short-term

memory than your users!

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A Chunk is 1 item in short term memory

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0121 414 2626

HEC ATR ANU PTH ETR EET

Microsoft product keys

Put your pens down for a minute and watch the screen

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Long-term memory (LTM)

• Repository for all our knowledge– slow access ~ 1/10 second– slow decay, if any– huge or unlimited capacity

• Two types of access structure– episodic – serial memory of events

– semantic – structured memory of facts, concepts, skills

semantic LTM derived from episodic LTM

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Interesting trivia

• Mega memory techniques– Combine episodic and semantic

• Experienced programmers– Use chunked techniques that they have

used before to solve problems– They decompose the problem into bigger

chunks than a novice programmer– Then apply known solution to each chunk– Takes about 10 years to build up repertoire

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Long-term memory (cont.)

• Semantic memory structure– provides access to information– represents relationships between bits of information– supports inference

• Model: semantic network– inheritance – child nodes inherit properties of parent

nodes– relationships between bits of information explicit– supports inference through inheritance

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LTM - semantic network

Mind map exercise

mind map our 3 lectures on ‘the human’

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Models of Long Term Memory - Frames• Information organized in data structures• Slots in structure instantiated with values for instance

of data• Type–subtype relationships

DOG

Fixed legs: 4

Default diet: carniverous sound: bark

Variable size: colour

COLLIE

Fixed breed of: DOG type: sheepdog

Default size: 65 cm

Variable colour

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Models of LTM - Scripts

Model of stereotypical information required to interpret situation

Script has elements that can be instantiated with values for context

Script for a visit to the vet

Entry conditions: dog illvet openowner has money

Result: dog betterowner poorervet richer

Props: examination tablemedicineinstruments

Roles: vet examines diagnoses treatsowner brings dog in pays takes dog out

Scenes: arriving at receptionwaiting in roomexaminationpaying

Tracks: dog needs medicinedog needs operation

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Models of LTM - Production rulesLTM is not only ‘facts’ it is also ‘rules’

Representation of procedural knowledge.

Condition/action rules if condition is matchedthen use rule to determine action.

IF dog is wagging tailTHEN pat dog

IF dog is growlingTHEN run away

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LTM - Storage of information

• rehearsal– information moves from STM to LTM

• total time hypothesis– amount retained proportional to rehearsal time

• distribution of practice effect– optimized by spreading learning over time

• structure, meaning and familiarity– information easier to remember

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LTM - Forgetting

decay– information is lost gradually but very slowly

interference– new information replaces old: retroactive

interference– old may interfere with new: proactive inhibition

so may not forget at all memory is selective …

… affected by emotion – can subconsciously `choose' to forget

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LTM - retrieval

recall – information reproduced from memory can be

assisted by cues, e.g. categories, imagery

recognition– information gives knowledge that it has been seen

before– less complex than recall - information is cue

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Applying this to your learning

• Mind maps• Pre-read• Take notes• Revise • Look for connections between subjects

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What knowledge do you have your users will not have?

• How much of what we have covered today is general knowledge?

• How hard is it for a user to build up a mental model of an interface?– Do site maps work?– Do you use them?

• What can you do to help?